The 1000Base-SX standard specifies an auto-negotiation protocol to automatically select the mode
of operation. In addition to duplex operation, the GEM ASIC can auto-negotiate
for IEEE 802.3x frame based flow control capabilities. The GEM PCS is capable
of performing auto-negotiation using the remote (or link partner) link end and receives
the capabilities of the remote end. It selects the highest
common demoninator mode of operation based on priorities. The ge driver also
supports forced-mode operation under which the driver selects the mode of operation.

APPLICATION PROGRAMMING INTERFACE

The cloning character-special device /dev/ge is used to access all ge
controllers installed within the system.

ge and DLPI

The ge driver is a Style 2 data link service provider.
All M_PROTO and M_PCPROTO type messages are interpreted as DLPI primitives. Valid
DLPI primitives are defined in <sys/dlpi.h>. Refer to dlpi(7P) for more information.

You must send an explicit DL_ATTACH_REQ message to associate the opened stream
with a particular device (ppa). The ppa ID is interpreted as an
unsigned long data type and indicates the corresponding device instance (unit) number. An error
(DL_ERROR_ACK) is returned by the driver if the ppa field value does
not correspond to a valid device instance number for the system. The
device is initialized on first attach and de-initialized (stopped) upon last detach.

The values returned by the driver in the DL_INFO_ACK primitive in response
to the DL_INFO_REQ are:

Maximum SDU is 1500 (ETHERMTU - defined in <sys/ethernet.h> ).

Minimum SDU is 0.

dlsap address length is 8.

MAC type is DL_ETHER.

sap length value is –2, meaning the physical address component is followed immediately by a 2 byte sap component within the DLSAP address.

Service mode is DL_CLDLS.

Quality of service (QOS) is not supported; accordingly, QOS fields are 0.

Once in the DL_ATTACHED state, you must send a DL_BIND_REQ to associate
a particular Service Access Pointer (SAP) with the stream. The ge driver
interprets the sap field within the DL_BIND_REQ as an Ethernet type; accordingly,
valid values for the sap field are in the [0-0xFFFF] range.
Only one Ethernet type can be bound to the stream at any time.

If you select a sap with a value of 0, the receiver
will be in 802.3 mode. All frames received from the media with
a type field in the range [0-1500] are assumed to be 802.3 frames
and are routed up all open streams bound to sap value 0.
If more than one stream is in 802.3 mode, the frame
will be duplicated and routed up multiple streams as DL_UNITDATA_IND messages.

In transmission, the driver checks the sap field of the DL_BIND_REQ to
determine if the sap value is 0 and the destination type field
is in the range [0-1500]. If either is true, the driver computes the
length of the message, not including initial M_PROTO mblk (message block), of
all subsequent DL_UNITDATA_REQ messages and transmits 802.3 frames of that value in the
MAC frame header length field.

The ge driver DLSAP address format consists of the 6 byte physical
(Ethernet) address component followed immediately by the 2 byte sap (type) component
producing an 8 byte DLSAP address. Applications should not hard code to this
particular implementation-specific DLSAP address format, but use information returned in the DL_INFO_ACK
primitive to compose and decompose DLSAP addresses. The sap length, full DLSAP
length and sap physical ordering are included within the DL_INFO_ACK. The physical
address length can be computed by subtracting the sap length from the full
DLSAP address length or by issuing the DL_PHYS_ADDR_REQ to obtain the current
physical address associated with the stream.

Once in the DL_BOUND state, you may transmit frames on the Ethernet
by sending DL_UNITDATA_REQ messages to the ge driver. The ge driver will
route received Ethernet frames up all open and bound streams having a sap
which matches the Ethernet type as DL_UNITDATA_IND messages. Received Ethernet frames
are duplicated and routed up multiple open streams if necessary. The DLSAP address
contained within the DL_UNITDATA_REQ and DL_UNITDATA_IND messages consists of both the sap
(type) and physical (Ethernet) components.

ge Primitives

The DL_ENABMULTI_REQ and DL_DISABMULTI_REQ primitives enable/disable reception of individual multicast group addresses. A
set of multicast addresses may be iteratively created and modified on a
per-stream basis using these primitives. The DL_ENABMULTI_REQ and DL_DISABMULTI_REQ primitives are accepted by
the driver in any state following DL_ATTACHED.

With the DL_PROMISC_PHYS flag set in the dl_level field, the DL_PROMISCON_REQ and
DL_PROMISCOFF_REQ primitives enable/disable reception of all promiscuous mode frames on the media including
frames generated by the local host. When used with the DL_PROMISC_SAP flag
set, this enables/disables reception of all sap (Ethernet type) values. When used
with the DL_PROMISC_MULTI flag set, this enables/disables reception of all multicast group
addresses. The effect of each is always on a per-stream basis and
independent of the other sap and physical level configurations on the stream
or other streams.

The DL_PHYS_ADDR_REQ primitive returns the six octet Ethernet address currently associated (attached)
to the stream in the DL_PHYS_ADDR_ACK primitive. This primitive is valid
only in states following a successful DL_ATTACH_REQ.

The DL_SET_PHYS_ADDR_REQ primitive changes the 6 octet Ethernet address currently associated (attached)
to the stream. The credentials of the process which originally opened the
stream must be superuser or EPERM is returned in the DL_ERROR_ACK.
The DL_SET_PHYS_ADDR_REQ primitive is destructive and affects all other current and future
streams attached to this device. A M_ERROR is sent up all other
streams attached to the device when DL_SET_PHYS_ADDR_REQ is successful on the stream.
Once changed, all streams subsequently opened and attached to the device will
obtain the new physical address. Once changed, the physical address will
remain until DL_SET_PHYS_ADDR_REQ is used to change the physical address again or
the system is rebooted, whichever comes first.

ge DRIVER

By default, the ge driver performs auto-negotiation to select the mode
and flow control capabilities of the link. The link can be in
one of the following modes:

1000 Mbps, full-duplex

1000 Mbps, half-duplex

Symmetric pause

Asymmetric pause

Speeds and modes are described in the 1000Base-TX standard.

The auto-negotation protocol automatically selects:

Operation mode (half-duplex or full-duplex)

Flow control capability (Symmetric and/or Asymmetric)

The auto–negotiation protocol:

Gets all the modes of operation supported by the link partner.

Advertises its capabilities to the link partner.

Selects the highest common denominator mode of operation based on the priorities.

When by default, auto-negotiation is used to bring up the link and
select the common mode of operation with the link partner, the GEM
hardware is capable of all of the operating modes listed above. The
PCS also supports forced-mode of operation under which the driver can select
the mode of operation and flow control capabilities using the ndd utility.

The GEM device also supports programmable Inter-Packet Gap (IPG) parameters ipg1 and
ipg2. By default, the driver sets ipg1 to 8 byte-times
and ipg2 to 4 byte-times, (the standard values.) You may want to alter
these values from the standard 1000 Mpbs IPG set to 0.096 microseconds.

ge Parameter List

You can use the ge driver to set and get parameters for
the GEM device. The parameter list includes current transceiver status, current link
status, inter-packet gap, PCS capabilities and link partner capabilities.

The PCS has two set of capabilities. One set reflects the capabilities
of the hardware and are read-only. The second set are read/write and
are used in speed selection and reflect the values you choose. At
boot time, both sets will be the same. The link partner capabilities
are read only and cannot be modified.